Generally, a vehicle wheel is configured with material including steel, aluminum, and the like. Such a vehicle wheel is fixed to a wheel hub of a vehicle, which is configured with a brake drum or a brake disc.
To improve fuel efficiency of a vehicle, lightweight material including aluminum and the like, or a design change in which a thickness is reduced is applied to a vehicle wheel.
Typically, when a vehicle wheel is designed, a structure including a hub mounting portion, a spoke portion, and the like is designed to satisfy a predetermined strength condition, and then slimming is performed on the hub mounting portion, an inside of the spoke portion, and the like so as to reduce a weight.
There is a problem in that vibration and noise occur at a vehicle wheel when the vehicle is driving due to lack of stiffness as a weight of the vehicle wheel is reduced, and the hub mounting portion, the inside of the spoke portion, and the like are reinforced so as to prevent such vibration and noise, and further, when an overall shape of the vehicle wheel is thicker, there is problem in that the weight is increased again.
Technology in which a hollow chamber is formed at a rim to reduce a weight and noise is prevented is disclosed in Korean Patent Application Publication No. 10-2006-0044653 (hereinafter, referred to as ‘Known Art Document 1’).
Technology in which a hollow is formed at a rim and a spoke is disclosed in Korean Patent Application Publication Nos. 10-2007-0053386 and 10-1999-0062973 in addition to Known Art Document 1, and a method of forming the hollow chamber is effective to reduce a weight and absorb a sound but there is a problem in that the method is vulnerable to durability.
Also, technology in which a hollow chamber is formed at a rim and then an aluminum foaming core is filled in the hollow chamber to absorb vibration and noise is disclosed in Korean Patent Application Publication No. 10-2007-0053386 (hereinafter, referred to as ‘Known Art Document 2’). Technology in which a hollow chamber is formed at a rim and a spoke and then an aluminum foaming core is filled in the hollow chamber has a higher effect in a sound absorption compared to Known Art Document 1, but there is a problem in that an effect in a weight reduction is limited.
Such a conventional vehicle wheel, as shown in FIGS. 1 and 2, includes a rim portion 3 formed to extend from an outer circumferential surface of a disc member 2 in one direction, and a tire 1 is mounted on an outer circumferential surface of the rim portion 3 as shown in FIG. 2.
That is, an outer bead 1a of one end of beads 1a and 1b at both ends of the tire 1 is seated on an outer bead seat 3a of the rim portion 3 configuring an outer surface of the disc member 2, and an inner bead 1b of the other end is seated on an inner bead seat 3b formed at a free end of the rim portion 3.
Meanwhile, the rim portion 3 is formed such that a thickness of a well portion 31 protruding from the disc member 2 is different from that of the inner bead seat 3b, the well portion 31 includes an outer well portion 31a formed to extend from the outer bead seat 3a and an inner well portion 31b formed to extend from the inner bead seat 3b and connected to the outer well portion 31a, and the inner well portion 31b is formed to be inclinedly bent from the outer well portion 31a to an outward side.
In a thickness of each of the well portion 31 and the inner bead seat 3b, which are formed as described above, the inner bead seat 3b provided with the inner bead 1b of the tire 1 is formed to have a largest thickness, the outer well portion 31a extending and protruding from the outer bead seat 3a is formed to have a next thick thickness, and the inner well portion 31b between the outer well portion 31a and the inner bead seat 3b is formed to have a smallest thickness.
The vehicle wheel formed as described above receives a load corresponding to a weight of a vehicle when the vehicle is driving through a road surface, and loads F1 and F2 delivered to the vehicle wheel are delivered through both beads 1a and 1b of the tire 1 as shown in FIG. 2.
As shown in FIG. 2, however, the loads F1 and F2, which are delivered through the tire 1, respectively act on the outer bead seat 3a of the rim portion 3 through the outer bead 1a of the tire 1 and on the inner bead seat 3b of the rim portion 3 through the inner bead 1b of the tire 1, and reaction forces R1 and R2 against the loads F1 and F2 respectively act on the outer bead seat 3a and the inner bead seat 3b of the tire 1.
Particularly, the reaction force R2 against the load F2, which acts on the inner bead seat 3b of the rim portion 3, acts as a reaction force R2′ transferred to the outer well portion 31a having one end connected to the outer bead seat 3a. 
Therefore, the reaction force R1 linearly acts against the load F1 in an opposite direction to serve an action and a reaction with respect to the load F1 acting on the outer bead seat 3a, whereas the reaction force R2 against the load F2 is transferred as the reaction force R2′ of the outer well portion 31a and thus the reaction force R2′ acts against the load F2 acting on the inner bead seat 3b. 
Consequently, since an amount of deformation ε1 occurs at the inner bead seat 3b and a thickness of the outer well portion 31a is relatively thinner than that of the inner bead seat 3b so that a supporting surface as a fixed end portion is small, there are problems in that deformation occurs from the fixed end portion of the outer well portion 31a such that an entire amount of deformation ε1 becomes large, and vibration corresponding to the amount of deformation ε1 is delivered to a hub (not shown) of the vehicle through a spoke portion 22 of the vehicle wheel to be generated as vibration and noise of the vehicle without a loss. Therefore, there is a need to address such problems.